/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_mult_q31.c
*
* Description:	Q31 vector multiplication.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
*
* Version 0.0.5  2010/04/26
*    incorporated review comments and updated with latest CMSIS layer
*
* Version 0.0.3  2010/03/10
*    Initial version
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup BasicMult
 * @{
 */

/**
 * @brief Q31 vector multiplication.
 * @param[in]       *pSrcA points to the first input vector
 * @param[in]       *pSrcB points to the second input vector
 * @param[out]      *pDst points to the output vector
 * @param[in]       blockSize number of samples in each vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function uses saturating arithmetic.
 * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.
 */

void arm_mult_q31(
    q31_t* pSrcA,
    q31_t* pSrcB,
    q31_t* pDst,
    uint32_t blockSize)
{
	uint32_t blkCnt;                               /* loop counters */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */
	q31_t inA1, inA2, inA3, inA4;                  /* temporary input variables */
	q31_t inB1, inB2, inB3, inB4;                  /* temporary input variables */
	q31_t out1, out2, out3, out4;                  /* temporary output variables */

	/* loop Unrolling */
	blkCnt = blockSize >> 2u;

	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* C = A * B */
		/* Multiply the inputs and then store the results in the destination buffer. */
		inA1 = *pSrcA++;
		inA2 = *pSrcA++;
		inA3 = *pSrcA++;
		inA4 = *pSrcA++;
		inB1 = *pSrcB++;
		inB2 = *pSrcB++;
		inB3 = *pSrcB++;
		inB4 = *pSrcB++;

		out1 = ((q63_t) inA1 * inB1) >> 32;
		out2 = ((q63_t) inA2 * inB2) >> 32;
		out3 = ((q63_t) inA3 * inB3) >> 32;
		out4 = ((q63_t) inA4 * inB4) >> 32;

		out1 = __SSAT(out1, 31);
		out2 = __SSAT(out2, 31);
		out3 = __SSAT(out3, 31);
		out4 = __SSAT(out4, 31);

		*pDst++ = out1 << 1u;
		*pDst++ = out2 << 1u;
		*pDst++ = out3 << 1u;
		*pDst++ = out4 << 1u;

		/* Decrement the blockSize loop counter */
		blkCnt--;
	}

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4u;

#else

	/* Run the below code for Cortex-M0 */

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

#endif /* #ifndef ARM_MATH_CM0 */

	while(blkCnt > 0u) {
		/* C = A * B */
		/* Multiply the inputs and then store the results in the destination buffer. */
		*pDst++ =
		    (q31_t) clip_q63_to_q31(((q63_t)(*pSrcA++) * (*pSrcB++)) >> 31);

		/* Decrement the blockSize loop counter */
		blkCnt--;
	}
}

/**
 * @} end of BasicMult group
 */
